Atmosphere-ocean oxygen and productivity dynamics during early animal radiations

TY - JOUR

T1 - Atmosphere-ocean oxygen and productivity dynamics during early animal radiations

AU - Dahl, Tais W.

AU - Connelly, James N.

AU - Li, Da

AU - Kouchinsky, Artem

AU - Gill, Benjamin C.

AU - Porter, Susannah

AU - Maloof, Adam C.

AU - Bizzarro, Martin

PY - 2019

Y1 - 2019

N2 - The proliferation of large, motile animals 540 to 520 Ma has been linked to both rising and declining O2 levels on Earth. To explore this conundrum, we reconstruct the global extent of seafloor oxygenation at approximately submillion-year resolution based on uranium isotope compositions of 187 marine carbonates samples from China, Siberia, and Morocco, and simulate O2 levels in the atmosphere and surface oceans using a mass balance model constrained by carbon, sulfur, and strontium isotopes in the same sedimentary successions. Our results point to a dynamically viable and highly variable state of atmosphere-ocean oxygenation with 2 massive expansions of seafloor anoxia in the aftermath of a prolonged interval of declining atmospheric pO2 levels. Although animals began diversifying beforehand, there were relatively few new appearances during these dramatic fluctuations in seafloor oxygenation. When O2 levels again rose, it occurred in concert with predicted high rates of photosynthetic production, both of which may have fueled more energy to predators and their armored prey in the evolving marine ecosystem.

AB - The proliferation of large, motile animals 540 to 520 Ma has been linked to both rising and declining O2 levels on Earth. To explore this conundrum, we reconstruct the global extent of seafloor oxygenation at approximately submillion-year resolution based on uranium isotope compositions of 187 marine carbonates samples from China, Siberia, and Morocco, and simulate O2 levels in the atmosphere and surface oceans using a mass balance model constrained by carbon, sulfur, and strontium isotopes in the same sedimentary successions. Our results point to a dynamically viable and highly variable state of atmosphere-ocean oxygenation with 2 massive expansions of seafloor anoxia in the aftermath of a prolonged interval of declining atmospheric pO2 levels. Although animals began diversifying beforehand, there were relatively few new appearances during these dramatic fluctuations in seafloor oxygenation. When O2 levels again rose, it occurred in concert with predicted high rates of photosynthetic production, both of which may have fueled more energy to predators and their armored prey in the evolving marine ecosystem.

KW - Cambrian explosion

KW - Global biogeochemical cycles

KW - Oxygenation

KW - Stable isotopes

KW - Uranium

U2 - 10.1073/pnas.1901178116

DO - 10.1073/pnas.1901178116

M3 - Journal article

C2 - 31501322

AN - SCOPUS:85072632935

SN - 0027-8424

VL - 116

SP - 19352

EP - 19361

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

IS - 39

ER -